Hit Point Depletion 

With the first method, the demon's physical form is destroyed by physical means.  A demonic summoned creature always has hit points, armour class, and a BAtCh rating.  Many demonic forms have one or more missile or melee attack routines but are usually incapable of parrying (unless noted otherwise in the monster description.)  If a summoned creature loses all of its hit points, it crumbles away to ash and dust.  A creature dispelled in this way cannot be summoned for one day per level of the last attacker.  The summoner of the creature is unaffected by a dispelling of this type.